1. Field of the Invention
The present invention relates to a cable connecting apparatus, a cable assembly, and a method of making the cable assembly. The cable connecting apparatus is used to collectively connect a plurality of differential signal transmission cables to a cable connector, each of the differential signal transmission cables transmitting differential signals whose phases are shifted by 180 degrees.
2. Description of the Related Art
Some electrical apparatuses, such as servers, rooters, storage devices, for handling high speed digital signals of several Gbit/s or higher, are compliant with a differential interface standard, such as low-voltage differential signaling (LVDS). Between such apparatuses or between circuit boards in such apparatuses, differential signals are transmitted through differential signal transmission cables. By using differential signaling, reduction in the voltage of a system power source is realized. Moreover, differential signaling is resistant to extraneous noise.
A differential signal transmission cable includes a pair of signal line conductors. A positive signal and a negative signal, whose phases are shifted by 180 degrees, are transmitted through the respective signal line conductors. A signal level is represented by the voltage difference between these two signals. For example, an apparatus on the receiving side recognizes that the signal level is “High” when the voltage difference is positive and the signal level is “Low” when the voltage difference is negative.
Japanese Unexamined Patent Application Publication No. 2012-099434 (FIGS. 1 and 2), for example, discloses a technology related to a differential signal transmission cable for transmitting differential signals. In the technology described in Japanese Unexamined Patent Application Publication No. 2012-099434 (FIGS. 1 and 2), a differential signal transmission cable includes a pair of signal line conductors extending parallelly with a predetermined distance therebetween. The signal line conductors are covered with an insulator. In other words, the insulator holds the signal line conductors so that the signal line conductors extend parallelly with a predetermined distance therebetween. The insulator is covered with a sheet-like outer conductor, and the outer conductor is covered with a sheath, which is a protective cover.
By stripping an end portion of the differential signal transmission cable in a stepwise manner, parts of the signal line conductors and a part of the outer conductor are exposed to the outside. A shield connection terminal, which is made of a metal, is connected to an exposed portion of the outer conductor by being crimped. The shield connection terminal includes a metal plate and a solder connection pin that is integrally formed with the metal plate. When the metal plate is crimped, the metal plate becomes plastically deformed so as to follow the shape of the outer conductor. Thus, the outer conductor and the shield connection terminal are electrically connected to each other, and the outer conductor is electrically connected to a ground pad of a circuit board through the shield connection terminal.